Understanding Camera Lens Filters

While using a wide-angle lens, if you wish to use more than one lens filter, you should use a slim/thin version of the filters to avoid vignetting at the image corners.

Camera filters are the glass elements that are added to your camera, either for protecting it, or for enhancing some of the characteristics of the clicked images. These filters come in different forms―screw-on, square and rectangular, drop-ins, series, gel, bayonet mounts, multi-coating, etc.

Most popular lens filters are screw-on and rectangular filters. Screw-on filters fit in the threads of the lens barrel, while rectangular filters slip into the filter holder that is placed on the lens' adapter ring.

The lens filters always enhance the important characteristics of the images by color correction or improving contrast or image brightness. Hence, it is necessary to use these filters to define minute details of the photograph. Here we have a quick look of the different filters and their purpose of usage.

UV/Haze
• Improve image quality
• Protect lens

Polarizing
• Reduce reflection
• Increase contrast
• Improve saturation

Graduated Neutral Density
• Control light gradients

Neutral Density
• Enable greater motion blurring

Color Balancing
• Color correction
• Changing white balance

Soft Focus
• Reduce sharpness of image

Filter for B&W images
• Block specific wavelengths of light

Now that we have seen the most common forms of lens filters, let us take a detailed look at the filters that are popularly used to enhance image characteristics.

Photography Type: Any

Ultraviolet light effects long distance shots or photographs taken at higher altitude. A bluish/purplish tint appears on the images, or there is a low-contrast haze on the images, which diminishes many details of the shot.

Thus, you don't get clear images. To avoid this, you need to mount a UV filter that absorbs the ultraviolet light without adversely affecting the light. Images clicked with a UV filter have a warm, amber appearance. These transparent or clear type filters protect the lenses from scratch, dirt, water particles, etc.

Photography Type: Focus on sky/water/foliage in landscape photography.

Photographs taken in broad daylight usually contain reflected sunlight spread over the focus areas of the image. This takes the attention away from the focal points of the photo. Polarizing filters are used to darken light skies, and reduce reflections from water or glass surfaces.

The contrast between important objects in the image (say, sky and cloud) is increased. Atmospheric haze is also reduced by this filter. However, polarization is angle-dependent. The right angle between your thumb and forefinger (the rule of thumb) is needed to get the desired effect.

The maximum effect of the polarization will be seen in the direction where your thumb points. However, the flip side of using this filter is the unnatural dark effect that the filter adds to the photograph.

Photography Type: Landscape photography (dramatically lit)

The GND filters have their half part clear, while their other half is dark. If you have bright spots in your photograph, you can align the dark part of the lens with it. This will help in balancing out the contrast in the image.

A hard-edge graduated neutral density filter is used in situations where there is a high contrast ratio, like a landscape photo with bright sky. Here, the hard edge is aligned with the sky, so as to darken it.

In a soft-edge graduated neutral density filter, there is a decrease in the darkness. So, you have a gradual transition from dark to clear, throughout the image.

Reverse GND filters have transition of dark to clear from the bottom to the top of the filter. Here, the dark part (hard-edge) is at the horizon and gradually decreases towards the top. So, in situations where you have to shoot the sun and its horizon, the contrast of the image is balanced out by using this filter type.

Photography Type: Waterfalls, Rivers, People in motion

Like the GND, the ND filters too are darkened or gray-toned. However, the gray-tone is throughout the lens, which absorbs calibrated degrees of light passing through the lens.

These filters are used when there is a need to balance out contrast between the focal points and shadows. Motion blurring is achieved by this filter because of its low shutter speed options.

These filters provide wider f-stops which slows down the shutter speed, thus, creating a foggy look to waterfall photographs. These filters are rectangular or circular type. You can stack more than one ND lens filter, but try not to overdo it because this may cause vignetting of the image.

Photography Type: Black and White Photography

Specially designed filters are required for shooting black and white photographs. There are blue, yellow, red, orange, and green filters for B&W photography. Each of these filters block certain wavelengths of light which, in turn, increases the monochrome color scheme of the image.

The red filter will block red light, while enhancing blue color, thus, giving the photograph a more deep and dark color. The green filter will lighten the green foliage in the photograph, and make it the main focal point by darkening the sky.

Photography Type: Any

Any photograph is made up of multiple colors, and not all of them are enhanced when you click the picture. You can adjust white balance of the camera to strike a balance with the light source and the scenic color scheme.

Color balancing filters will instill changes in the light source, so as to get brightly colored images. There are two forms of color balancing filters i.e. 85B (warm-up/orange filter) and 80A (cool-down/blue filter). With the advent of image processing software, these filters have fallen out of use.

Photography Type: Macro photography

These filters reduce the sharpness of the image up to an extent that is barely noticeable. These images retain the sharp edges, but blur the rest of the image to create a soft focus point.

Images taken by using these filters, can be reworked for correcting imperfect skin conditions. These lenses are generally used for macro photography, where it is necessary to capture the object up close.

Though filters add the necessary effects and enhance your photos, they can even damage your image. The overall image contrast can reduce, or lens flare can be caused by light reflecting from the filter. Even physical vignetting can be introduced if the lens are not fitted properly. Thus, it is necessary to choose the right kind of lens for your photography purpose.